Heating apparatus



Sept. 6, 1960 J. J. FOX

HEATING APPARATUS Filed July 9, 1959 N V E N TO R JO H N J. FOX

BYWY

ATTORNEY United States Patent HEATING APPARATUS John J. Fox, Lexington,Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh,Pa., 21 corporation of Pennsylvania Filed July 9, 1959, Ser. No. 826,0422 Claims. Cl. 219-38) This invention relates to immersion heaters formounting in an opening in the wall of a liquid heating vessel, and hasfor an object to provide an improved assembly for a heater of this type.

Another object of the invention is to provide rigid terminals in suchheaters for electrical line connections.

Yet another object of the invention is the elimination, from immersionelectrical heaters, of supporting terminal blocks for the terminalstrips without sacrifice of rigidity of the strips.

In apparatus of this type, it is important to keep the assembly ascompact and as simple as practical, both from the standpoint ofacceptance by the customer and from the cost standpoint. To beacceptable to'the customer, the device must have approval of theUnderwriters Laboratory. Where the terminal strips of immersion heaterconnections are unrestrained at their free ends, the UnderwritersLaboratory requires materially greater spacing of the strips from eachother and from the clamping plate than is required in constructionswhere the otherwise free ends of the strips are restrained. Hence,suitable restraining or anchoring of the free ends of the terminalstrips may result in compactness or reduction in size of the assembly,provided the means relied upon for anchoring the free ends of the stripsdoes not, in turn, complicate or enlarge the assembly.

The present invention effects suitable anchoring of the terminal stripsat their otherwise free ends, without any additional parts or anyenlargement of the assembly, and without reliance uponv insulatingblocks or the like.

This is accomplished by providing the mounting plate with a centralrecess which receives the terminal portions of the tubular sheath of theresistance heater, filling the recess with a body of thermal settinginsulating material which, when set, seals the sheath terminals, andforming the terminal strips in U-shape with one leg secured to aterminal pin of the heater and the free end of the other leg imbedded inthe body of thermal setting material and thereby anchored againsttwistmg.

The foregoing and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Fig. l is a perspective view of a heater assembly constructed inaccordance with the present invention; and

Fig. 2 is a horizontal sectional view, taken along the line 11-11 ofFig. 1, looking in the direction indicated by the arrows.

The heater assembly shown in the drawing includes the usual tubularsheathed electrical resistance heater 11, having a helical resistanceheating element 12 housed in a tubular sheath 13 and maintained spacedfrom the latter by suitable compacted insulating material 14 (Fig. 2).The heater 11 is carried by a mounting plate 16, centrally deformed toprovide a recess 18 and a surrounding flat flange 19. The terminalportions of the 2,951,929 Patented Sept. 6, 1960 sheath 13 extendthrough appropriate openings in the bottom wall of the recess 18 and aredisposed in the recess.

A clamping plate 21 is disposed in overlying relation to the flange 19of the mounting plate 16 and has a central opening aligned with therecess 18 of the mounting plate. The electrical heating element 12 isprovided with the usual terminal pins 22 projecting beyond the recess 18and provided with terminal strips 23 of U-shape disposed inside-by-side, essentially parallel spaced relation. One leg 24 of eachU-shaped terminal strip is permanently secured to a terminal pin 22 andthe other leg 25 of each terminal strip has its free end extending intothe recess 18.

A body of suitable thermal setting insulating material 26 is disposed inthe recess 18 and is of suflicient depth to extend upwardly into thecentral opening of the clamping plate 21 to contact the walls of thatopening, with the result that when the material 26 solidifies, it servesto hold together the clamping plate 21 and the mounting plate 16 andalso to hermetically seal the open ends of the heater sheath 13. Moreparticularly, the solidified thermal setting material 26 securelyanchors the free ends of the legs 25 of the U-shaped terminal strips 23,so that the strips cannot be readily bent or moved relative to eachother or to the clamping plate 21 when electrical connections are madethereto, as by tightening of lead connecting screws (not shown) receivedin the threaded openings 27 of the terminal strips 23.

Heating elements of this type must have minimum acceptable clearancesbetween current carrying parts and adjacent metallic structure. Wherethe free ends of the terminal strips of such devices are not anchored,greater spacing of the two terminal strips with respect to each otherand with respect to the adjacent clamping plate is required than isnecessary where the free end portions of the strips are securelyanchored. Accordingly, by anchoring such strips it is permissible to usecloser spacing of the parts and consequently provide a smaller structureutilizing less material with consequent reduced cost. The presentinvention, as above described, provides this desirable anchor of theterminal strips without the use of the usual insulating blocks orcorresponding anchoring means frequently utilized heretofore for thispurpose.

The assembled mounting and clamping plates are provided with the usualcorner bolt holes, for mounting of the assembly on a tank wall in theusual manner.

Summarizing, it will be apparent that by this invention, applicantutilizes a body of thermal setting insulating material disposed in arecess provided in the assembled structure to perform three essentialfunctions: that is, to hermetically seal the ends of the heater sheath,to retain the clamping plate in predetermined relation with respect tothe mounting plate, and to anchor the free ends of the terminal strips.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

What is claimed is:

1. An electrical heater assembly comprising a tubular sheathedelectrical resistance heater, a mounting plate for said heater, saidmounting plate having a central recess and a surrounding flange, thetubular sheath of said heater having terminal portions extending throughthe mounting plate into the recess thereof, terminal pins for theresistance heater extending from the ends of said sheath, a clampingplate overlying the mounting plate flange and having a central openingtherethrough overlying the mounting plate recess, a body of thermalsetting insulating material filling the recess and covering the terminalportions of the tubular sheath, and U-shaped terminal strips each havingone leg secured to one of the heater terminal pins and the other legembedded in the body of thermal setting insulating material.

2. An electrical heater assembly comprising a tubular sheathedelectrical resistance heater, a mounting plate for said heater, saidmounting plate having a central recess and a surrounding flange, thetubular sheath of said heater having terminal portions extending throughthe mounting plate into the recess thereof, terminal pins for theresistance heater projecting beyond the ends of said sheath terminalportions, U-shaped terminal strips disposed in side-by-side essentiallyparallel spaced relation and each having one leg secured to a terminalpin 4 and the other leg terminating in the recess of the mounting plate,and a body of thermal setting insulating material disposed in saidmounting plate recess, said material covering the terminal portions ofthe tubular sheath and anchoring said other legs of the U-shapedterminal strips.

References Cited in the file of this patent UNITED STATES PATENTS Boggset al. Nov. 8, 1955 2,860,227 Fox Nov. 11, 1958 FOREIGN PATENTS 488,370Great Britain July 5, 1938

